The solar energy is the energy which exemption the Sun by its radiation, directly or in a diffuse way through the atmosphere. In space the kinetic energy of the photons can be used to propel a solar Voile. On Ground, solar energy is at the origin of the Cycle of water and the Vent. The Vegetable kingdom, on which the Animal kingdom depends, also uses it by transforming it into chemical energy via the Photosynthèse. Except for the nuclear energy, Geothermics and tidal energy, solar energy is at the origin of all energies on Earth.
Thanks to various processes, it can be transformed into another form of useful energy for the human activity, in particular in Chaleur, electricity or biomass. By extension, the expression “solar energy” is often employed to indicate electricity or the heat obtained starting from the latter.
Techniques to collect solar energy
The techniques to directly collect part of this energy are available and are constantly improved. One can distinguish the solar liability , the photovoltaic solar and the solar thermics :
Photovoltaic solar energy
See also: photovoltaic Solar energy
Photovoltaic solar energy indicates the electricity produced by transformation of part of the solar radiation with a photovoltaic Cellule. Several cells are connected enters on a photovoltaic solar Module. Several modules are gathered to form a solar installation at a private individual or in a photovoltaic Solar power station , which feeds an electric distribution network.
The photovoltaic term can indicate is the physical phenomenon, the photovoltaic effect discovered by Antoine Becquerel in 1839, or associated technology.
Thermal solar energy
See also: thermal Solar energy
Solar thermics consists in using the heat of the solar radiation. It is declined in various ways: thermodynamic solar power stations, solar water-heaters and heating, solar cooling, solar cookers and driers.
Heliothermodynamic solar energy
See also: Solar power station thermodynamics
Solar thermodynamics is a solar technique which uses solar thermics to produce electricity just like photosynthesis.
Passive solar energy
See also: Solar energy passivates
The oldest solar energy utilization consists in profiting from the direct contribution of the solar radiation, i.e. the solar energy passivates. So that a building profits as well as possible from the rays of the Sun, one must take account of solar energy at the time of the architectural design (double frontages, orientation towards the south, surfaces glazed, etc). The thermo isolation plays a big role to optimize the proportion of the passive solar contribution in the heating and the lighting of a building.
In a solar Maison passivates, the passive solar contribution allows to make important energy saving.
In the buildings whose design is known as Bioclimatique, the solar energy passivates also makes it possible to heat whole or part of a building for a Coût proportional quasi no one.
Economic aspect
Majority of the studies serious (Kenneth Deffeyes, professor at the University of Princeton, 2006; Fredrik Robelius, of the University of Uppsala in Sweden, 2007) show that the production of oil reached a peak on the level of 84,5 million barrels per day. Oil cannot compensate for the increase in the energy needs any more. The forecasts also indicate a fall of the production between 2008 and 2018.
To compensate for the fall to come from the oil importations, it is essential to start as of being equipped today in renewable energies. The solar one brings an inexhaustible source of energy and the European commission for renewable energies expects that solar energy will represent a share of 20% in renewable energies, those having to bring 20% of energy in 2020 and 50% in 2040.
Systems of production of solar energy
The systems of production of solar energy have a Coût proportional quasi no one: once the installation of the apparatus carried out, energy is produced by the Sun, which does not cost anything. It is however necessary to take account of the capital costs and the maintenance of the apparatus.The use of thermal Solar panels is justified to produce medical warm water with lower costs. Once the installation carried out, maintenance is far from expensive and makes it possible to make substantial savings of fossile fuel or electricity.
On the other hand, for the solar photovoltaic one, the cost of the installation is increased enough, although research progresses in this field. Several countries (like the France and the Germany) thus set up systems of financial incentive (in particular tax: Tax credit) to the installation of solar panels. In France, the tax credit of the State is supplemented according to the areas and the departments by financial aids which apply as well to solar photovoltaic, as with the solar thermics or work of energy saving (like the improvement of the thermo isolation or the installation of a powerful boiler).
The use of system of production of solar energy is also justified in the situations where it is very expensive to import fossile fuels or to transport electricity, as in isolated zones ou/et little populated. In France, the electrification of many refuges in mountain and insolated villages in Guyana were carried out by a photovoltaic solar field, sometimes coupled to a auxiliary Generator.
Geography
The Désert of Mojaves in the south-west of the the United States is one of the principal areas energy producers solar of the world with a full capacity of 354 MWReceived solar energy depends on:
- the Latitude: towards the equator the Angle of incidence is close to 90° thus enlightened surface is smaller and energy is concentrated.
- the nebulosity (Nuage S), which is important at the equator and weaker in intertropical medium.
History
Augustin Mouchot starts to be interested in solar energy in 1860. In 1873, a subsidy of the general advice of Tours enables him to build a Solar furnace of 4 m ² which it presents to the Academy of Science in October 1875. In 1877, a subsidy of the general advice of Algiers enables him to build on the same principle a “large apparatus of 20 m ²” which receive a Gold medal with the World Fair of 1878. In August 1882, at the time of the Festival of the French Union of youth, Abel Pifre uses a solar receiver of Augustin Mouchot to actuate a Steam engine which enables him to draw a Journal.
Chronology
Solar energy in the present and the future
Boom of the solar objects
There is a score of years appeared the solar pocket calculator. Some photovoltaic cells replaced the batteries advantageously there, poisons for the environment. Today, of the stores dedicated to ecology, but also of the signs plus general public, many objects propose functioning with solar energy: torches, lamps of garden, radio-alarms, mobiles animated, watches… Proof that solar energy allures the consumers by the image " verte" that it conveys. Its other asset is its wandering side: solar chargers make it possible from now on to feed in electricity, where that one is, a mobile phone, a GPS or a laptop. For the travellers with the long course, there exist even back bags equipped with solar collectors. Some imagine the clothing also equipped with photovoltaic cells, to connect its walkman MP3 directly there.
Is the sun the energy of tomorrow?
Battery chargers, ventilators, lamps of garden, hydraulic pump… Today, all or almost can function with solar energy. The fighter must from now on carry in his bag a GPS equipped with a solar charger, and photovoltaic panels appear on all the roofs. Essential to the life on ground, the sun can render many other services to us: to heat our dwellings, to feed in energy the most moved back places…
Projects of powerplants are born in many areas of the world. The potential is immense: " 5% of the surface of the deserts would make it possible to produce all the electricity of the planet " , affirm Patrick Jourde and Jean-Claude Muller, researchers with the Police station of atomic energy (ECA) and with CNRS. " Theoretically, it would be enough in France to carry out the only southern part of the roofs in photovoltaic modules to produce all national electrical energy (550 terawattheures, càd thousand billion wattheures, per annum ". Remained a long time with the drag, France wants to fill its delay today. Thus a National institute of solar energy was created in August 2006, of which the objective is to improve solar technologies in order to make them more competitive.
Panels on the roofs
The photovoltaic panels convert the sunlight into electricity. In France, thanks to the tax assistances of the state, the private individuals are increasingly numerous to be equipped some. The energy not consumed by the hearth is recovered by EDF, is held since 2002 to repurchase the renewable electricity of origin produced by the private individuals or the communities.
The photovoltaic one with large scales
The photovoltaic power station most powerful in the world (350 000 solar panels out of 114 ha) is in the course of construction with the Portugal. After the power station of Chambéry, inaugurated in 2005, France beat its own record with a new installation with the Réunion, in 2006. The Suisse is it also launched in the race with solar and, in Germany, the 57 000 panels of the Bavaria solarpark function since 2005.
Projects of the solar towers
A solar collecting vase out of glass heats the ambient air, which, while going up at high speed in the tower, actuates turbines generating of electricity. A first prototype of solar tower, with Manzanares, in Spain, proved reliable as of 1982. The project Australia N consists, him, in a tower of almost 1 000 m height which should provide the equivalent of the consumption of 200 000 hearths. The Spain considers on its side the construction of a 750 m height solar tower, able to feed 120 000 hearths.
The opening of the thermo plants
The principle of thermal electrical energy is to concentrate the rays of the sun, using parabolic mirrors, worms of the tubes containing a conducting fluid of heat. When this one warms up, it produces heat which actuates turbines generating of electricity. Certain States, the Spain at the head, misent on this technology rather than on the photovoltaic one, whose blow of production proves higher because of the price of the Silicium which imposes electric eyes.Spain thus has since 2005 the largest solar power station thermal of Europe, of a power of 100MW. Some: 400000 mirrors, is a surface of 1,1 million square meters, will collect the energy of the Sun.
The France has projects of less importance but which shows a will of promotion of this type of energy as the future power station of the Rest whose construction should begin mid- 2008.
Energy anywhere
In the countries of the South, where the sunning is very important, the solar one can provide to the rural regions energy necessary for lightings, the refrigerators, the hydraulic pumps or to the installations of telecommunication. Supported by ONG, projects of electrification of villages are in hand in many countries of Africa and South America.
To heat itself by the sun
In the town of Almere, with the Netherlands, a " island solaire" will be built in summer 2007. It will cover, in 2008, thanks to thermal solar panels, 10% of the energy needs of 2 700 hearths. A surface of 4 m ² of thermal panels indeed makes it possible to meet the requirements out of warm water for a hearth for four people and to divide by two, at least, its invoice of heating.
Reference
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